Capture and Retention of Cryptosporidium parvum Oocysts by Pseudomonas aeruginosa Biofilms

The association of Cryptosporidium oocysts with biofilm communities can influence the propagation of this pathogen through both environmental systems and water treatment systems. We observed the capture and retention of C. parvum oocysts in Pseudomonas aeruginosa biofilms using laboratory flow cells. Biofilms were developed in two different growth media using two different strains of P. aeruginosa, a wild-type strain (PAO1) and a strain that overproduces the exopolysaccharide alginate (PDO300). Confocal laser-scanning microscopy was used in conjunction with image analysis to assess the structure of the biofilms prior to introducing oocysts into the flow cells. More oocysts were captured by the biofilm-coated surfaces than the abiotic glass surface in both media. There was no significant difference in capture across the two strains of P. aeruginosa biofilm, but the fraction of oocysts captured was positively related to biofilm roughness and surface-area-to-volume ratio. Once captured, oocysts were retained in the biofilm for more than 24 h and were not released after a 40-fold increase in the system flow rate. We believe the capture and retention of oocysts by biofilm communities can impact the environmental transmission of C. parvum, and this interaction should be taken into consideration when predicting the migration of pathogens in the environment.     

Loss of Drp1 function alters OPA1 processing and changes mitochondrial membrane organization

RNAi mediated loss of Drp1 function changes mitochondrial morphology in cultured HeLa and HUVEC cells by shifting the balance of mitochondrial fission and fusion towards unopposed fusion. Over time, inhibition of Drp1 expression results in the formation of a highly branched mitochondrial network along with “bulge”-like structures. These changes in mitochondrial morphology are accompanied by a reduction in levels of Mitofusin 1 (Mfn1) and 2 (Mfn2) and a modified proteolytic processing of OPA1 isoforms, resulting in the inhibition of cell proliferation. In addition, our data imply that bulge formation is driven by Mfn1 action along with particular proteolytic short-OPA1 (s-OPA1) variants: Loss of Mfn2 in the absence of Drp1 results in an increase of Mfn1 levels along with processed s-OPA1-isoforms, thereby enhancing continuous “fusion” and bulge formation. Moreover, bulge formation might reflect s-OPA1 mitochondrial membrane remodeling activity, resulting in the compartmentalization of cytochrome c deposits. The proteins Yme1L and PHB2 appeared not associated with the observed enhanced OPA1 proteolysis upon RNAi of Drp1, suggesting the existence of other OPA1 processing controlling proteins. Taken together, Drp1 appears to affect the activity of the mitochondrial fusion machinery by unbalancing the protein levels of mitofusins and OPA1.     

Liver-derived IGF-I regulates exploratory activity in old mice

Growth hormone (GH) replacement in hypopituitary patients improves well-being and initiative. Experimental studies indicate that these psychic effects may be reflected in enhanced locomotor activity in mice. It is unknown whether these phenomena are mediated directly by GH or by circulating IGF-I. IGF-I production in the liver was inactivated at 6-10 wk of age (LI-IGF-I-/- mice), resulting in an 80-85% reduction of circulating IGF-I, and, secondary to this, increased GH secretion. Using activity boxes on three different occasions during 1 wk, 6-mo-old LI-IGF-I-/- mice had similar activity levels, and 14-mo-old mice had a moderate but significant decrease in activity level, compared with control mice. At 20 mo of age, the LI-IGF-I-/- mice displayed a more prominent decrease in activity level with decreased horizontal activity throughout the test period, and at day 1, there were several signs of an altered habituation process with different time patterns of locomotor activity and horizontal activity compared with the control mice. At days 3 and 5, rearing activity was lower in the 20-mo-old LI-IGF-I-/- mice. Anxiety level was unaffected in all age groups, as measured using the Montgomery's elevated plus-maze. In conclusion, old LI-IGF-I-/- mice displayed a decrease in both horizontal and rearing (exploratory) activity level and an altered habituation process. These results indicate that liver-derived IGF-I mediates at least part of the effects of GH on exploratory activity in mice.     

Effects of mother-infant skin-to-skin contact on severe latch-on problems in older infants: a randomized trial

Background

Infants with latch-on problems cause stress for parents and staff, often resulting in early termination of breastfeeding. Healthy newborns experiencing skin-to-skin contact at birth are pre-programmed to find the mother’s breast. This study investigates if skin-to-skin contact between mothers with older infants having severe latching on problems would resolve the problem.

Methods

Mother-infant pairs with severe latch-on problems, that were not resolved during screening procedures at two maternity hospitals in Stockholm 1998–2004, were randomly assigned to skin-to-skin contact (experimental group) or not (control group) during breastfeeding. Breastfeeding counseling was given to both groups according to a standard model. Participants were unaware of their treatment group. Objectives were to compare treatment groups concerning the proportion of infants regularly latching on, the time from intervention to regular latching on and maternal emotions and pain before and during breastfeeding.

Results

On hundred and three mother-infant pairs with severe latch-on problems 1–16 weeks postpartum were randomly assigned and analyzed. There was no significant difference between the groups in the proportion of infants starting regular latching-on (75% experimental group, vs. 86% control group). Experimental group infants, who latched on, had a significantly shorter median time from start of intervention to regular latching on than control infants, 2.0 weeks (Q₁ = 1.0, Q₃ = 3.7) vs. 4.7 weeks (Q₁ = 2.0, Q₃ = 8.0), (p-value = 0.020). However, more infants in the experimental group (94%), with a history of “strong reaction” during “hands-on latch intervention”, latched-on within 3 weeks compared to 33% in the control infants (Fisher Exact test p-value = 0.0001). Mothers in the experimental group (n = 53) had a more positive breastfeeding experience according to the Breastfeeding Emotional Scale during the intervention than mothers in the control group (n = 50) (p-value = 0.022).

Conclusions

Skin-to-skin contact during breastfeeding seems to immediately enhance maternal positive feelings and shorten the time it takes to resolve severe latch-on problems in the infants who started to latch. An underlying mechanism may be that skin-to-skin contact with the mother during breastfeeding may calm infants with earlier strong reaction to “hands on latch intervention” and relieve the stress which may have blocked the infant’s inborn biological program to find the breast and latch on.

Trial registration

Karolinska Clinical Trial Registration number CT20100055     

Sexually selected nest-building--Pomatoschistus minutus males build smaller nest-openings in the presence of sneaker males

Both natural selection and sexual selection may act on nest-building. We tested experimentally how different regimes of egg-predation and male-male competition influence nest-building before mating, using the marine fish sand goby, Pomatoschistus minutus. Males with sneaker males present built the smallest nest-openings, smaller than males held alone or with Pomatoschistus microps males (which may predate eggs and compete over nest-sites but not compete over fertilizations). Males with visual access to other nest-building males tended also to build smaller openings than males held alone or with P. microps. Males with egg-predators present built nests with openings not differing significantly from any other treatment. Our results indicate that the small nest-openings found in the sneaker male treatment are sexually selected through protection against sneaking or by female choice. Across treatments, time span before a male started to build his nest also explained variation in nest-opening width; males starting late built larger nest-openings.     

What happens in Vegas,better stay in Vegas: <Emphasis Type="Italic">Phragmites australis</Emphasis> hybrids in the Las Vegas Wash

While hybridization between Native and Introduced Phragmites australis has not been documented across much of North America, it poses an ongoing threat to Native P. australis across its range. This is especially true for native populations in the biologically rich, but sparsely distributed wetlands of the southwest United States, which are among the most imperiled systems in North America. We identified multiple Hybrid P. australis stands in the Las Vegas Wash watershed, NV, a key regional link to the Colorado River basin. Rapid urbanization in this watershed has caused striking changes in water and nutrient inputs and the distribution of wetland habitats has also changed, with urban wetlands expanding but an overall reduction in wetland habitats regionally. Native P. australis has likely been present in the Wash wetland community in low abundance for thousands of years, but today Hybrid and Native plants dominate the shoreline along much of the Wash. In contrast, Introduced P. australis is rare, suggesting that opportunities for novel hybridization events remain uncommon. Hybrid crosses derived from both the native and introduced maternal lineages are widespread, although the conditions that precluded their establishment are unknown and we did not find evidence for backcrossing. Spread of Hybrid plants is likely associated with flooding events as well as restoration activities, including revegetation efforts and construction for erosion control, that have redistributed sediments containing P. australis rhizomes. Downstream escape of Hybrid plants to Lake Mead and wetlands throughout the lower Colorado River basin is of management concern as these Hybrids appear vigorous and could spread rapidly.     

Microbial rRNA gene expression and co‐occurrence profiles associate with biokinetics and elemental composition in full‐scale anaerobic digesters

This study examined whether the abundance and expression of microbial 16S rRNA genes were associated with elemental concentrations and substrate conversion biokinetics in 20 full‐scale anaerobic digesters, including seven municipal sewage sludge (SS) digesters and 13 industrial codigesters. SS digester contents had higher methane production rates from acetate, propionate and phenyl acetate compared to industrial codigesters. SS digesters and industrial codigesters were distinctly clustered based on their elemental concentrations, with higher concentrations of NH₃‐N, Cl, K and Na observed in codigesters. Amplicon sequencing of 16S rRNA genes and reverse‐transcribed 16S rRNA revealed divergent grouping of microbial communities between mesophilic SS digesters, mesophilic codigesters and thermophilic digesters. Higher intradigester distances between Archaea 16S rRNA and rRNA gene profiles were observed in mesophilic codigesters, which also had the lowest acetate utilization biokinetics. Constrained ordination showed that microbial rRNA and rRNA gene profiles were significantly associated with maximum methane production rates from acetate, propionate, oleate and phenyl acetate, as well as concentrations of NH₃‐N, Fe, S, Mo and Ni. A co‐occurrence network of rRNA gene expression confirmed the three main clusters of anaerobic digester communities based on active populations. Syntrophic and methanogenic taxa were highly represented within the subnetworks, indicating that obligate energy‐sharing partnerships play critical roles in stabilizing the digester microbiome. Overall, these results provide new evidence showing that different feed substrates associate with different micronutrient compositions in anaerobic digesters, which in turn may influence microbial abundance, activity and function.     

Climate impacts on transocean dispersal and habitat in gray whales from the Pleistocene to 2100

Arctic animals face dramatic habitat alteration due to ongoing climate change. Understanding how such species have responded to past glacial cycles can help us forecast their response to today's changing climate. Gray whales are among those marine species likely to be strongly affected by Arctic climate change, but a thorough analysis of past climate impacts on this species has been complicated by lack of information about an extinct population in the Atlantic. While little is known about the history of Atlantic gray whales or their relationship to the extant Pacific population, the extirpation of the Atlantic population during historical times has been attributed to whaling. We used a combination of ancient and modern DNA, radiocarbon dating and predictive habitat modelling to better understand the distribution of gray whales during the Pleistocene and Holocene. Our results reveal that dispersal between the Pacific and Atlantic was climate dependent and occurred both during the Pleistocene prior to the last glacial period and the early Holocene immediately following the opening of the Bering Strait. Genetic diversity in the Atlantic declined over an extended interval that predates the period of intensive commercial whaling, indicating this decline may have been precipitated by Holocene climate or other ecological causes. These first genetic data for Atlantic gray whales, particularly when combined with predictive habitat models for the year 2100, suggest that two recent sightings of gray whales in the Atlantic may represent the beginning of the expansion of this species' habitat beyond its currently realized range.